Piston



1927' G. w. ROBINSON PISTON Filed July 15, 1925 2 Sheets-Sheet 1 INVENTOR. EORGE W. ROBINSON M 2 w. m M 2, e N w R M% m wk m .fi, w MW 4 G. W. ROBINSON PISTON Filed July 15,- 1925 Patented Oct. 11, 1927.

UNITED STATES 15645256 PATENT OFFICE.

GEORGE W. ROBINSON, OF SAN DIEGO, CALIFORNIA, ASSIGNOR F ONE-HALF TO 13. N. V

' DOBLAND, OF SAN DIEGO, CALIFORNIA.

PISTON.

Application filed July 15, 1925. Serial No. 43,826.

My invention relates to pistons for internal combustion engines and a purpose of my invention is the provision of an expansible piston in which is incorporated means by which it can be positively expanded to eflect an increase in its diameter so that when wear occurs either upon the peripheral surface of the piston or upon the wall of its cylinder, the resulting clearance is eliminated and a close running fit between piston and cylinder maintained at all times, thereby entirely eliminating what is generally known as piston sla as well as greatly prolonging the life of the piston rings,

ring ooves, wrist pins and cylinder walls, where y maximum working efiiciency and long life of the engine will be insured.

Another purpose of my invention is the provision of an expanding elementwhich is capable of bein adjusted so as to efi'ect an expansion of the skirt without removal of the piston from its cylinder, the expanding element being in the form of a cam which can be adjusted to expand the skirt at the thrust or working side of the piston so that when adjustment of the skirt is efiected the ring lands of the piston will be held clear of the cylinder wall and the piston maintained in perfect alinement.

I will describe only four forms of piston embodying my invention and will then point out the novel features thereof in claims.

In the accompanying drawings Figure 1 is a view in longitudinal vertical as section of one form of piston embodying my invention.

Figure 2 is a view in longitudinal ver-- tioal section taken on the line 22 of Figure 1 looking in the direction of the arrows.

Figure 3 is a horizontal sectional view taken on the line 3-3 of Figure 1 and lookin I in the direction of the arrows.

Figure 4 is a fragmentary horizontal sectional view taken on the line 4- 31: of Figure 1 looking in the direction of the arrows.

Figure 5 is a longitudinal vertical sectional view illustrating another form of piston embodying my invention.

Figure 6 is a longitudinal vertical sectional view taken on the line 6-6 of Figure 5 and looking in the direction of the arrows.

Figure 7 is a view in side elevation lookg in the direction of the arrows 77 of Figure 5.

Figure 8 is a longitudinal vertical sectional view of still another form of piston embodying my invention.

Figure 9 is a longitudinal vertical sec tional view taken on the line 99 of Figure 8.

Figure 10 is a longitudinal vertical sectiona-l view of a further form of piston embodying my inventio Figure 11 is a longitudinal vertical sec tional view taken on the line 11-11 of Fig ure 8 and looking in the direction of the arrows.

Figure 12 is a fragmentary view in side elevation of the piston embodied in the two preceding views.

Referring specifically to the drawings in which similar reference characters'refer to similar parts in each of the several views and particularly to Figures 1 to 4, inclusive, I have herein shown a piston formed of an integral body of suitable metal to provide a head H from which extends a tubular body or skirt S, the piston having the usual annular grooves and journals for the packing 1rings and wrist pin (not shown) respective y.

The skirt S is slotted longitudinally at diametrically opposite points as indicated at 15 and 16, and the inner ends ofthe slots communicate with relatively wide slots 17 and 18 extending circumferentially of the skirt. Other slots 19. extend longitudinally of the skirt from the opposite ends of the slot 17 towards the free end of the skirt and terminate in relatively short transverse slots 20, so as to divide the skirt into a pair of exnansible sections E and E".

The sections E and E" are adapted to be expanded interiorly at the upper end of the slot 15 through the medium of a movable expanding element A having a cam surface 21 co-acting with a cam surface 22 formed on a stationary abutment member B. The element A. is adapted to be moved longitudinally of the skirt so as to cause sliding movement of its cam surface 21 over the cam surface of the member B with a corresponding expansion of the sections E and E, by means of a feeding member in the form of a shaft 23 journaled in bearings 24 and 25 formed integral with the skirt S, the latter bearing bein divided. longitudinally by the slot 15 and aviug a tapered bore 25. The shaft 23 is reduced in diameter as indicated at 26 and its reduced portion extends freely W through a sleeve 27 formed upon the expanding element A and then into the journal 24. The body portion 28 of the shaft is of tapered form to provide a cam adapted to engage the bore and is threaded at 29 to receive a feed nut 30 having a flattened surface 31 engaging the inner wall of the skirt S so as to prevent rotation of the nut, while its free end is reduced and threaded as indicated at 32 to receive a lock nut- 33 having a washer 34. The shaft 23 is also provided r with akerf 35 so that a screw driver (not ill shown) may be readily inserted from the open end of the skirtand the shaft rotated as desired.

The stationary abutment member B is of L-shaped form with its vertical arm 36 provided with the cam surface 22 and its hori zontal arm 37 extending inwardly and perforated to receive a reduced portion-26 of the shaft 23, the shaft co-operating with a lip 38 formed on the element and extending into the slot 17 to maintain the element in fixed position with its vertical arm 36 engaging the inner surface of the skirt S in overlying relation to the slot 15.

In practice, the sleeve 27 of the element A abuts the shoulder formed between the portions 26 and 28 of the shaft 23, and the feed nut 30 abuts the upper end of the hear ing 25, .so that when the shaft is rotated in a clockwise direction it will be fed upwardly through the nut 30 thus causing its tapered body portion 28 to spread the lower portion of the expansible sections E and 1E, while the expanding element A will be forced upwardly so as to engage the cam surface 22, whereby an outward pressure will be exerted against the upper portion of the sections, the body portion 28 and element A co-operating to evenly expand the sections, along the length of the longitudinal slot 15.

Referring specifically to Figures 5 to 7,

inclusive, I have herein shown an embodi- (till ment of my invention in which the skirt S is slotted longitudinally at 39 with the inner end of the slot communicating with a transverse slot 40 from the ends of which extend oppositely diverging slots 41. Diametrically opposite to the slot 40 is a transverse slot 42 from one end of which extends diagonally a slot 43 to the free end of the skirt. By slotting the skirt in this manner a pair of expansible sections are formed which are adapted to be expanded at the slot 39 by means of an expanding element in the form of a shaft 44 journaled in a two part hearing 45 provided with a tapered bore to recame the tapered body portion 46 of the shaft. Threaded shanks 47 and 48 are formed at opposite ends of the body portion 46 and project from the ends of the bearing 45 so as to receive respectively a stationary feed nut 49 and a lock nut 56 having a washer 51. lit will be clear that by rotating menace embodiment of my invention in which the skirt of the piston is slotted longitudinally at 52 and transversely at 53, with the ends of the slot 53 communicating with relatively short diagonal slots 54 diverging from each other towards the free end of the skirt, and terminating at circular openings 55 which latter function to prevent fracturing of the skirt beyond the slot. By this arrangement of slots the skirt is adapted to be expanded at spaced points along the length of the slot 52 by means of a pair of expanding elements in the form of wedge shaped blocks, 56 and 57, the former having a threaded opening extending therethrough to receive the threaded portion 58 of a shaft 60 journaled in a. two part bearing 61 formed integral with the skirt of the piston near the free end of the slot 52. One side of the block 56 engages a cam surface 62 formed on an L shaped abutment 63 cast integral with the skirt of the piston above the transverse slot 53, and the opposite side of the block engages a cam surface 64 formed on a projection 65 cast integral with the skirt and divided longitudinally by the slot 52. The block 57 abuts a flange 66 formed upon the shaft 60 with its opposite sides engaging cam surfaces 67 and 68 formed on the confronting sides of the bearing 61. lhe shaft 60 is threaded at 59 in an opposed direction to the threaded portion 58 so as to receive a stationary feed nut 69 which abuts the upper end of the journal 61, while at the opposite end of the journal, a, lock nut 70 and a washer 71 are provided.

It will be clear that with a screw driver applied to a kerf 72 formed in the end of the shaft 61, rotation of the shaft in one direction will cause it to move upwardly through the feed nut 69, thus imparting upward movement to the block 57 through the medium of the flange 60 so as to cause the block to engage the cam surfaces. 67 and 68 and thus efiect expansion of the lower portion of the skirt, while at the same time the block 56 is-Inoved upwardly due to the opposed direction of its threads with respect to those of the feed nut 69 to cause'expansion of the upper portion of the skirt outwardly from the cam surface of the abutment 63, whereby an even expansion of the skirt will be efi'ected along the length of the slot 52.

lln the form shown in Figures 10 to 12, inclusive, the skirt of the piston is slotted in the same manner as in the preceding form and is adapted to be expanded at spaced points along the length of its longitual my pistons their skirts are slot bymeans of a pair of expanding elements 73 and 7 4, the former having a threaded opening extending therethrough to re ceive the threaded portion 75 of a shaft 77 provided with a reduced upper end 78 journaled in a bearing 79 and with its lower end journaled in a two part bearing 80. The expanding element 74- abuts a flange 81 formedonthe shaft 77 and projects into the longitudinal slot of the skirt in the form of a wedge adapted to engage cam surface 82 formed in thewalls of the slot, while the expanding element 73 is provided with a cam surface 83 adapted to engage correspondin 84 at eit er side of the slot. The body portion 76 of the shaft 77 is threaded opposite ly to the portion 75 to receive a stationary feed nut 85 and a lock nut 86, and it will be clear that by rotating the shaft in a clockwise direct-ion its u ward movement through the feed nut 85 Wlll cause upward sliding movements ofthe expanding elements 73 and 74 over their co-acting cam surfaces and thus effect an even expansion of the skirt along the length of its longitudinal slot.

It will be noted that in all the forms of split at two spaced points to their free edges, and that an expanding element or elements is provided at one only of the points so that the skirts can be expanded to effect a snug fit of the pistons in their cylinders when cold and yet are free to constrict at the other of said points when heated, thus positively preventing freezing or sticking of the pistons in their cylinders. By this arrange ment of slots and expanding elements the original adjustment is maintained for when the piston again cools the constricted skirt returns to its original diameter due to the it is constructed.

From the foregoing description, 7 it will be manifest that l have provided simple and durable means by which the split skirt of a piston can be ad usted to effect an expansion of the skirt when worn, thereby obviating the necessity of replacing a slightly worn piston with a new one, and greatly extending the timeat which a reboring of the cyl inder will be required.

Although I have herein shown and described only four forms of pistons embodying my invention, it is to be understood that various changes and'modifications may be made therein without departing from the spirit of the invention and the spirit and scope of the appended claims.

What I claim is:

1. A piston comprising a hollow body formed to provide a head having a skirt slotted longitudinally and transversely to provide a pair of expansible sections, our nals formed interior-1y of the skirt, one of cam surfaces formed on projections over the cam surface of said abutment when said shaft is rotated, whereby said abutment element and said body portion will function to expand said sections at spaced points and thus increase the diameter of the skirt.

2. A piston comprising a head having a slotted skirt, a feeding member comprising a shaft rotatably mounted on said skirt, means for imparting longitudinal movement to said shaft when rotated, and expanding elements arranged at spaced points upon said shaft and movable therewith in a manner to effect an expansion of said skirt when said shaft is rotated.

3. A piston comprising a head having a skirt provided at one side with intercommunicating slots arranged to provide a longitudinal slot extending to' the free edge of the skirt, a transverse slot at the inner endof said longitudinal slot, and diverging slots extending from the ends of said transverse slot, said skirt slotted at the opposite side to provide a transverse slot, and a diagonal slot communicating therewith and extending to the free edge of the skirt, a journal formed integral with the skirt and divided by said longitudinal slot, said journal having a tapered bore, a shaft having a tapered inherent flexib lity of the metal of whlch b d o y portion engaging said bore, threaded shanks on the ends of said body portion, a feed nut threaded on one of said shanks, and a lock nut threaded on the other of said shanks.

4. A piston comprising a head having a skirt provided with a longitudinal slot extending to its free end, a transverse slot communicating with the inner end of said first slot, diverging slots extending from said transverse slot towards the free end of said skirt and having enlarged ends, a journal formed integral with said skirt divided longitudinally by said first slotandhaving cam surfaces, an L-shaped abutment member formed integral with said skirt and hav ing a cam surface, a. projection formed on the skirt and having a cam surface, a shaft mounted in said journal and having oppositely threaded portions a shoulder formed on said shaft, an expanding element threaded on one portion of said shaft and having cam surfaces adapted to engage the cam surfaces of said abutment and skirt, a second expanding element threaded on the other portion of said shaft and having cam surfaces adapted to engage the cam surfaces of said journal, a stationary feed nut threadedly engaging said shaft for imparting longitudinal movement to said shaft when rotated, and a lock nut threaded on said shaft for locking the latter against movement.

5. A piston comprising a head having an integral slotted skirt provided with cam surfaces at spaced points along its length, expanding elements mounted for. movement in said skirt, and means for imparting movement to said elements to cause the latter to engage said cam surfaces and thereby efl'ect an increase in the diameter of the skirt uniformly along its length.

6. A piston comprising a head having a skirt slotted longitudinally at spaced points,

neaaaae and means for expandin the skirt at one only of said points to e eot a snug fit of the piston in its cylinder when cold, Wherehy said skirt is free to constrict at the other of said points when the piston is heated to thereby prevent freezing of the piston in its cylinder.

7. A piston having its skirt split at at least two points spaced circumferentially from each other to provide a pair of relatively expandible sections, and means for expanding the sections at one of the points for efiecting a snug fit of the piston in its cylinder When cold, said sections being free to constrict at the other of said points when the piston is heated, to thereby prevent sticking of the piston in its cylinder.

GEORGE W. ROBINSON. 

